Trace chemicals in water are typically measured in parts per million (ppm) and parts per billion
(ppb), which help us understand very small concentrations. They can also be measured in
parts per trillion (ppt).
PARTS PER MILLION (ppm)
Parts Per MILLION or Milligrams/Liter = 1 drop in 13.6 gallons
These measurements help us detect and manage even the tiniest concentrations.
PARTS PER BILLION (ppb)
Parts Per BILLION or Micrograms/Liter = 1 drop in 13,563 gallons
PARTS PER TRILLION (ppt)
Parts Per TRILLION or Nanograms/Liter = 1 drop in 13,563,368 gallons
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Annual Water Quality Report 2023
Important Info from the U.S. EPA on Drinking Water
Drinking water, including bottled water, may contain small amounts of some contaminants. The presence of
contaminants does not necessarily indicate the water poses a health risk. More information about contaminants and
potential health effects can be obtained by calling the U.S. EPA’s Safe Drinking Water Hotline at 1-800-426-4791 or
visiting the U.S. EPA’s website at www.epa.gov. Trace chemicals are measured in parts per million (ppm), the same as
milligrams per liter (mg/L). Some constituents are measured in parts per billion (ppb), the same as micrograms per
liter (ug/L). Some constituents are measured in parts per trillion (ppt), the same as nanograms per liter (ng/L).
Some people may be more vulnerable to contaminants in drinking water than the general population. Those who may
be particularly at risk include cancer patients, organ transplant recipients, people with HIV-AIDS or other immune
system disorders, some elderly individuals, and infants. These people should seek advice about drinking water from
their health care providers. U.S. Centers for Disease Control & Prevention (CDC) guidelines on appropriate means to
lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the Safe Drinking
Water Hotline at 1-800-426-4791 or by visiting water.epa.gov/Drink/Hotline.
ARSENIC
Your drinking water contains low levels of arsenic that fall within State and Federal health-based standards
and are below thresholds that would require corrective action. The U.S. Environmental Protection Agency
sets maximum levels for contaminants based on the best available treatment technology to remove them from
drinking water. The U.S. EPA continues to research the health effects of low levels of arsenic, a mineral known
to cause cancer in humans at high concentrations and linked to other health effects such as skin damage and
circulatory problems. In 2008, EVMWD completed construction on the Back Basin Groundwater Treatment
Facility that removes arsenic and other naturally occurring contaminants often found in groundwater.
LEAD
Since 2017, public schools have had the option to
request lead testing from local water agencies. New
regulations required these tests by July 1, 2019, for
all K-12 schools built before 2010. During 2018-19,
EVMWD tested drinking water at all K-12 public
schools in its service area, and none exceeded the
Action Level for lead. Elevated lead levels can cause
serious health problems, especially for pregnant
women and young children. Lead in drinking water
usually comes from service lines and home plumbing
materials. While EVMWD provides high-quality
drinking water, it cannot control the plumbing
materials used in homes.
To minimize lead exposure, flush your tap for 30
seconds to 2 minutes before drinking if the water has
been sitting for several hours. For more information
on lead in drinking water, testing methods, and ways
to reduce exposure, contact the Safe Drinking Water
Hotline at 1-800-426-4791 or visit www.epa.gov/
Safewater/Lead. In line with new federal regulations
released on Aug. 4, 2022, EVMWD is conducting a
lead and copper service line study. Although EVMWD
service lines do not contain lead, customer-side lines
may contain lead or steel, and older brass fixtures,
valves, or solder may also have lead. Homes built
before 1986 will be included in the survey. Throughout
2024, EVMWD staff will conduct the material survey
at service meters.
TDS
One of the most important issues facing water supplies
throughout Southern California today is salinity.
Total dissolved solids, a measure of salinity, includes
concentration of dissolved mineral salts such as calcium,
magnesium, sodium, sulfate, and chloride. Local water
supplies and recycled water have continued to show an
increase in salt content. Though these salts are viewed
as an aesthetic standard by the SWRCB-DDW, too
much salt can negatively impact our local water sources,
agriculture, and our environment. EVMWD is exploring
options on how to meet state-mandated requirements to
eliminate the overabundance of these salts.
RADON
Radon is a naturally occurring gas formed from the
normal radioactive decay of uranium. Radon has been
detected in our finished water supply. There are no
regulatory limits prescribed for radon levels in drinking
water. The pathway to radon exposure occurs primarily
through its presence in the air. Exposure over a long
period to air containing radon may cause adverse
health effects. If you are concerned about radon in
your home, testing is inexpensive and easy. For more
information, call your state radon program at 1-800-
745-7236, the National Safe Council’s Radon Hotline
at 1-800-SOSRADON or the U.S. EPA Safe Drinking
Water Act Hotline at 1-800-426-4791.
Note: EVMWD staff are currently surveying water service pipe materials to comply with State and Federal Lead and Copper
regulations. These surveys may continue beyond 2024. Many surveys will involve assessments at water meters with no
inconvenience to customers. Some surveys may cause service interruptions for additional verifications between the meter and
the dwelling structure. Residents will receive notifications.
REVISED TOTAL COLIFORM RULE
This water quality report reflects changes in drinking water
regulatory requirements during 2022. These revisions add
the requirements of the Federal Revised Total Coliform Rule,
effective since April 1, 2016, to the existing state Total Coliform
Rule. This rule protects public health by ensuring the integrity
of our drinking water distribution system and monitoring for
the presence of microbials, including total coliform and E. coli
bacteria. An additional benefit of this rule requires water systems
vulnerable to microbial contamination to identify and fix problems.
Water systems that exceed a specified frequency of total coliform
occurrences must conduct an assessment to determine if any
sanitary defects exist. If found, the water system must correct
these defects. The state Revised Total Coliform Rule became
effective July 1, 2021.
Understanding parts per million (ppm), parts per billion (ppb) and
parts per trillion (ppt) in water